A novel temperature-sensitive cationic hydrophobic cellulose ether: preparation and characterization

A temperature-sensitive polymer-hydroxyl isopropoxy triethyl ammonium chloride cellulose ether-was prepared from hydroxypropyl methyl cellulose (HPMC) and with epoxypropyl triethyl ammonium chloride as the hydrophobization reagent. Then, the reaction conditions of etherification reaction time, mass ratio of the etherifying agent to HPMC, molar ratio of alkali to etherifying agent, and concentration of HPMC were optimized. The structures of the products were characterized via nuclear magnetic resonance and infrared spectrum, and the temperature sensitivity was analyzed via ultraviolet spectrophotometry. It was found that the degree of substitution significantly affected the temperature sensitivity and lowest inversion temperature of the hydroxyl isopropoxy triethyl ammonium chloride cellulose ether. The effects of the substitution degree rising from 0.19 to 0.50 on the water retention value were explored. When the molar ratio of alkali to HPMC was constant, the water retention value declined with the increased substitution degree of cationic cellulose ether. The temperature rise of phase transformation in this process was fully reversible and nonhysteretic. Since the polymer variation originated from the change of intramolecular and intermolecular forces during the heating process, here the effects of addictive micromolecules on the regulator solution were further studied. As the NaOH concentration rose, the substitution degree and water retention value both first increased and then declined and both maximized at the NaOH concentration of 20.7%. Graphical abstract